In accordance with the invention, an area array connector is provided which is made up of the required number of electrically conductive connector elements or contacts carried in a three-layer laminated insulative housing. The contacts project from either side of the housing and are positioned to engage contact pads on printed circuit boards in a stack, the connector being interleaved between adjacent printed circuit boards.
More specifically, in accordance with the invention, there is provided an area array connector adapted to connect the contact pads on one generally planar circuit element, such as a printed wiring board, to the corresponding contact pads on another generally planar circuit element or printed circuit board. The connector includes an insulative contact mounting sheet having a plurality of contact mounting apertures in it. A plurality of electrically conducting contacts are mounted in the contact mounting apertures; each contact has contact pad engaging legs resiliently projecting away from opposite faces of the contact mounting sheet. Two insulative contact securing sheets are provided; one laminated to each face of the contact mounting sheet. Each contact securing sheet has apertures in it to accommodate the resiliently projecting legs of said contacts.
In a preferred embodiment of the invention, each of the electrically conducting contacts has a base leg adapted and proportioned to fit in and engage the contact mounting apertures of the contact mounting sheet and two pad engaging legs which are cantilevered resiliently outwardly from the base leg in opposite directions. In accordance with one preferred embodiment, it is preferred that the pad engaging legs of the contacts have a shorter linear extent than the base legs of the contacts. In such embodiment, in order to assure that the contacts are securely held in position, it is preferred that the contact mounting apertures are each greater in linear extent than the corresponding apertures of the contact securing sheets. In accordance with another embodiment, it is preferred that the pad engaging legs of the contacts have substantially the same length as the base legs of the contacts. In this embodiment, it is preferred that the thickness or width of at least part of the base legs be greater than the thickness or width of the pad engaging legs. It is further preferred in all embodiments that the contact mounting apertures are each greater in area than the corresponding apertures in the contact securing sheets.
In accordance with the invention, it is preferred that the contacts are aligned with one another in a staggered pattern, or alternately that the contacts are aligned with one another in a rectangular array, in which the spacing between adjacent contact projecting leg ends is less than the length of a projecting contact leg, and further in which the contacts are skewed with respect to the alignment of the rectangular array to accommodate the length of the projecting contact leg.
In accordance with another aspect of the invention, an assembly of a plurality of generally planar circuit elements is provided. The circuit elements have contact pads on at least one surface thereof, and are stacked one upon another, with area array connectors being interleaved between adjacent circuit elements. The area array connectors are made up of an insulative contact mounting sheet which has a plurality of contact mounting apertures therein, a plurality of electrically conducting contacts mounted in the contact mounting apertures, each contact having contact pad engaging legs resiliently projecting away from opposite faces of the contact mounting sheet, and two insulative contact securing sheets, one laminated to each face of the contact mounting sheet. Each contact securing sheet has apertures therein to accommodate the resiliently projecting legs of the contacts. Framing means are provided for holding the assembly together and for establishing pressure contact between the contact pads and corresponding contact pad engaging legs. It is preferred to have spacer means mounted in the sheets to establish and maintain a uniform thickness of the connector.
In accordance with still another aspect of the invention, there is provided a method for making an area array connector adapted to connect contact pads on one generally planar circuit element to corresponding contact pads on another generally planar circuit element that includes providing an insulative generally planar contact mounting sheet, selecting positions on the contact mounting sheet at which contacts are desired to be mounted, and laser machining contact-accommodating apertures in the contact mounting sheet at said selected positions thereon. Contacts of conducting material are formed, each contact having a mounting leg for fitting into and engaging the contact-accommodating apertures, and further having contact pad engaging legs resiliently projecting away from opposite faces of the contact mounting sheets. The contacts are mounted in the contact-accommodating apertures. Two insulative contact securing sheets are provided having apertures laser machined therein which are registerable with the projecting legs of contacts mounted in the contact mounting sheet. One of the apertured contact securing sheets is adhesively laminated to each face of the contact mounting sheet.